Medium
1013 on Worcester Bosch Greenstar 8000 Style System

Your boiler has reached its maximum power limit while trying to heat your water, and it has stopped for a short time to prevent overheating.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Max. combustion point reached

From this model's manual
Verified against the Worcester Bosch Greenstar 8000 Life Style installation & service manual, page 77.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the boiler generates more heat than the system can successfully carry away, leading to a sudden temperature spike. The most common cause is a restriction in water flow, often due to a failing internal pump or a buildup of sludge and debris blocking the main heat exchanger. It essentially means the boiler is working too hard to push heat into a system that isn't circulating properly.

This issue often becomes more apparent during winter when the boiler is required to run at higher power levels for longer periods to meet central heating demands.

DIY fix possible

Check that all your radiator valves are fully openEnsure your system pressure is topped up to between 1.0 and 1.5 barPress the 'Reset' button on the front of the screen to clear the temporary lockout

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